Slagging gasifier ready after extensive tests
The slagging gasifier is capable of processing strongly caking and swelling coal. No difference in gasification performance has been noted with regard to gasifying weak or strongly caking high volatile bituminous coals. Overall performance of the gasifier with different types of coal is about the same. The outlet temperatures of the unit are much lower than for entrained flow gasifiers. Consequently, there is no need for the complex equipment necessary for heat recovery. These characteristics result in considerable reductions in capital costs. A high thermal efficiency is also achieved since the gasifier requires lower coal feeds per unit of gas output. Slag tapping from the Westfield gasifier is carried out automatically and requires no operator attention. The molten slag is quenched in water released from the system. The crude gas contains tar, some entrained solids and some steam derived from the moisture in the coal feed. The gasification process also yields phenols, chlorine, nitrogen, as well as sulphur-containing compounds. On cooling the gas, tars and leftover steam condense to yield a tar containing a variety of impurities and an aqueous solution. The tar can be recycled by either being pumped to the top of the bed or through the tuyeres. The aqueous solutions can be processed by conventional solvent extraction, ammonia stripping, and effluent treatment. Phenols recovered from the process can be sold as chemical feedstock or reycled to the gasifier. Cooled gas is purified using several available processes. The most common is the Rectisol process. In this process, hydrogen sulphide, carbonyl sulphide, ammonia, and other compounds are removed by bringing the gas in contact with methanol. The clean and dry gas obtained is a mixture of carbon monoxide, hydrogen, and methane. It can be used as a fuel gas or for synthesis natural gas (SNG) production.
- OSTI ID:
- 5668487
- Journal Information:
- World Coal; (United States), Vol. 8:1
- Country of Publication:
- United States
- Language:
- English
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